The present invention relates to the programming of an electrically operated appliance in which it is desired to operate the device for a selected program interval during which various operations are performed in a desired sequence. Program controllers of this type are employed in household appliances such as microwave cooking ovens and clothes dryers. In appliance applications of the aforesaid type, the appliance operator selects a desired sequence of operation by prepositioning a control member such as a push button or lever on the appliance control panel and then selects a program interval on a timer control for energizing the timer to actuate the various appliance control functions during time-out of the program interval.
Examples of such programmer timer devices and techniques for electrical appliance programming are those described in my copending applications Ser. No. 490,269, filed May 2, 1983, now U.S. Pat. No. 4,523,062 and Ser. No. 495,895, filed May 18, 1983. In these earlier copending applications, I have described a timing mechanism employing a ratchet and pawl advance mechanism for a switch-actuating program cam. The aforesaid described ratchet and pawl advance mechanism employs a toothed ratched wheel having two arcuate segments of teeth of different root diameters. A masking ratchet employing sequenced deep notches permits the single oscillating advance pawl to contact the ratchet teeth of the lowest root diameter only upon predetermined multiples of the pawl stroke for giving plural advance rates to the ratchet wheel.
In addition, the aforesaid copending applications describe a system for cycling an auxiliary appliance function at subintervals of the program interval during a dwell period in the program cam advance upon completion and time-out of the appliance program interval. The problem encountered with subinterval cycling of the appliance function during dwell of the program cam is that it has heretofore not been possible to provide a way or means of automatically restarting the program cam advancement with a single ratchet advance pawl mechanism once the pawl has reached a toothless portion of the ratchet wheel for interrupting the advance of the cam.
Heretofore, in programmer/timers for controlling appliances, where it has been desired to provide plural cycling rates of the appliance during the program interval, multiple timing advance mechanisms employing more than one timing motor and cam advance mechanism have been required to provide the plurality of program cam advancement. Thus it has long been desired to provide a simple, low cost controller timer for an appliance which employs only a single timing motor with a single-pawl ratchet advance mechanism and provide for plural rates of advance of the program cam. It has further been long desired to provide continued subinterval duty cycling of the appliance function after time-out of the main program interval without requiring the ratchet advance mechanism to reach a dwell in order to provide the subinterval cycling.